Systems, devices, and methods for holographic optical elements

ABSTRACT

Systems, devices, and methods for holographic optical elements are described. A holographic optical element includes a first layer of holographic material and a second layer of holographic material. The first layer of holographic material includes a first hologram responsive to light in a first waveband and a second hologram responsive to light in a second waveband. The second layer of holographic material includes a third hologram responsive to light in a third waveband and may include a fourth hologram responsive to light in a fourth waveband. The first, second, third, and fourth wavebands are distinct and may comprise light of red, blue, green, and infrared wavelengths, respectively. Distribution of the three or four holograms on two layers of holographic material allows each hologram to have an index modulation of greater than 0.016, a diffraction efficiency of greater than 15%, and an angular bandwidth of greater than 12°.

TECHNICAL FIELD

The present systems, devices, and methods generally relate toholographic optical elements and particularly relate to holographicoptical elements in wearable heads-up displays.

BACKGROUND Description of the Related Art Wearable Heads-Up Displays

A head-mounted display is an electronic device that is worn on a user'shead and, when so worn, secures at least one electronic display within aviewable field of at least one of the user's eyes, regardless of theposition or orientation of the user's head. A wearable heads-up displayis a head-mounted display that enables the user to see displayed contentbut also does not prevent the user from being able to see their externalenvironment. The “display” component of a wearable heads-up display iseither transparent or at a periphery of the user's field of view so thatthe display does not completely block the user from being able to seetheir external environment. Examples of wearable heads-up displaysinclude: the Google Glass®, the Optinvent Ora®, the Epson Moverio®, andthe Sony Glasstron®, just to name a few. Wearable heads-up displays mayemploy holographic optical elements to create and display an image tothe user.

Holographic Optical Elements

For the purposes of the present systems, devices, and methods, aholographic optical element is an optical element that includes at leastone hologram. Generally, a holographic optical element comprises a layerof holographic material with at least one hologram recorded, embedded,stored, or carried (collectively, “included”) therein or thereon.Several parameters can be used to define the function of a holographicoptical element including index modulation, diffraction efficiency, andangular bandwidth. The index modulation of a holographic optical elementis the change in the holographic material refractive index from beforethe hologram is recorded to after the hologram is recorded and is anindication of the ability of the holographic optical element to diffractlight. The diffraction efficiency is the ratio of the power of the lightdiffracted by the holographic optical element to the power of the lightincident on the holographic optical element and can be represented as apercentage. The angular bandwidth of the holographic optical element isthe range of angles of incidence which are diffracted by the holographicoptical element. If a single layer of holographic material is recordedwith multiple holograms, the total index modulation and diffractionefficiency of the holographic optical element is divided amongst theindividual holograms. Consequently, there is less index modulation anddiffraction efficiency available for each hologram when multipleholograms are present.

Photopolymer

A photopolymer is a material that changes one or more of its physicalproperties when exposed to light. The changes may be manifested indifferent ways, including structurally and/or chemically. Photopolymermaterials are often used in holography as the film or medium within orupon which a hologram is recorded. For example, a photopolymer film maybe controllably exposed/illuminated with a particular interferencepattern of light to cause surface relief patterns to form in/on thephotopolymer film, the surface relief patterns conforming to theinterference pattern of the illuminating light. It is these changes inphysical properties of the photopolymer that determine the indexmodulation, diffraction efficiency, and angular bandwidth of a hologramas discussed above. A photopolymer film may comprise only photopolymermaterial itself, or it may comprise photopolymer carried on or betweenany or all of: a substrate, such as triacetate and/or polyamide and/orpolyimide and/or polycarbonate, and/or a fixed or removable protectivecover layer. Many examples of photopolymer film are available in the arttoday, such as DuPont HRF photopolymer film, Darol™ photopolymer fromPolygrama Inc., or Bayfol® HX film from Bayer AG.

BRIEF SUMMARY

A holographic optical element may be summarized as including a firstlayer of holographic material that includes a first hologram and asecond hologram and a second layer of holographic material that includesat least a third hologram, wherein each of the first hologram, thesecond hologram, and the at least a third hologram has a respectiveindex modulation of at least 0.016. The first hologram may be responsiveto light in a first waveband and unresponsive to light outside of thefirst waveband, the second hologram may be responsive to light in asecond waveband and unresponsive to light outside of the secondwaveband, and the third hologram may be responsive to light in a thirdwaveband and unresponsive to light outside of the third waveband,wherein the first waveband, second waveband, and third waveband are alldistinct from one another with no overlap therebetween. The firstwaveband, the second waveband, and the third waveband may include: a redwaveband comprising light of red wavelengths, a green wavebandcomprising light of green wavelengths, and a blue waveband comprisinglight of blue wavelengths.

The second layer of holographic material may further include a fourthhologram that is responsive to light in a fourth waveband andunresponsive to light outside of the third waveband, wherein the fourthwaveband is distinct from the first waveband, the second waveband, andthe third waveband with no overlap therebetween. The first waveband, thesecond waveband, the third waveband, and the fourth waveband mayinclude: a red waveband comprising light of red wavelengths, a greenwaveband comprising light of green wavelengths, a blue wavebandcomprising light of blue wavelengths, and an infrared wavebandcomprising light of infrared wavelengths.

The first layer of holographic material may further include a firstsurface and a second surface, wherein the first surface of the firstlayer of holographic material is opposite the second surface of thefirst layer of holographic material across a thickness of the firstlayer of holographic material, and the second layer of holographicmaterial may have a first surface and a second surface, wherein thefirst surface of the second layer of holographic material is oppositethe second surface of the second layer of holographic material across athickness of the second layer of holographic material, and theholographic optical element may further include: a first layer ofsubstrate having a first surface and a second surface, the first surfaceof the first layer of substrate opposite the second surface of the firstlayer of substrate across a thickness of the first layer of substrate, asecond layer of substrate having a first surface and a second surface,the first surface of the second layer of substrate opposite the secondsurface of the second layer of substrate across a thickness of thesecond layer of substrate, and a third layer of substrate having a firstsurface and a second surface, the first surface of the third layer ofsubstrate opposite the second surface of the third layer of substrateacross a thickness of the third layer of substrate; wherein: the firstsurface of the first layer of holographic material is physically coupledto the first surface of the first layer of substrate, the second surfaceof the first layer of holographic material is physically coupled to thefirst surface of the second layer of substrate, the first surface of thesecond layer of holographic material is physically coupled to the secondsurface of the second layer of substrate, and the second surface of thesecond layer of holographic material is physically coupled to the firstsurface of the third layer of substrate. The material of the first layerof substrate, the material of the second layer of substrate, and thematerial of the third layer of substrate may each be selected from agroup consisting of: polycarbonate, polyamide, polyimide, andtriacetate.

The holographic optical element may be curved. A respective diffractionefficiency of each of the first hologram, the second hologram, and thethird hologram may be at least 15%. A respective angular bandwidth ofeach of the first hologram, the second hologram, and the third hologrammay be at least 12°. The first layer of holographic material and thesecond layer of holographic material may have a thickness not greaterthan 8 μm. The holographic material may be a photopolymer.

A method of producing a holographic optical element that comprises afirst layer of holographic material and a second layer of holographicmaterial wherein the first layer includes a first hologram responsive toa first waveband of light and a second hologram responsive to a secondwaveband of light, and the second layer includes a third hologramresponsive to a third waveband of light, wherein each of the firstwaveband, the second waveband, and the third waveband is distinct andnon-overlapping, may be summarized as including: mounting the firstlayer of holographic material on a planar transparent surface; recordingthe first hologram and the second hologram in the first layer ofholographic material, wherein recording includes exposing the firstlayer of holographic material to light in the first waveband and lightin the second waveband simultaneously to provide respective indexmodulations of at least 0.016 to the first hologram and the secondhologram; mounting the second layer of holographic material on a planartransparent surface; recording the third hologram in the holographicmaterial wherein recording includes exposing the second layer ofholographic material to light in the third waveband to provide an indexmodulation of at least 0.016 to the third hologram; and adhering thefirst layer of holographic film and the second layer of holographicfilm. Recording the first hologram and the second hologram in the firstlayer of holographic material may further includes: simultaneouslyexposing the first layer of holographic material to light in the firstwaveband having a first power and light in the second waveband having asecond power for a first length of time to provide an index modulationof 0.016 to both the first hologram and the second hologram; andrecording the third hologram in the second layer of holographic materialmay further include: exposing the second layer of holographic materialto light in the third waveband having a third power for a second lengthof time to provide an index modulation of 0.016 to the third hologram.

The second layer of holographic film may further include a fourthhologram responsive to a fourth waveband of light, wherein the fourthwaveband of light is distinct from the first waveband, the secondwaveband, and the third waveband with no overlap therebetween, and themethod may further include: recording the fourth hologram in the secondlayer of holographic material, wherein recording includes exposing thesecond layer of material to light in the fourth waveband concurrentlywith the recording of the third hologram to provide an index modulationof at least 0.016 to the fourth hologram.

A first surface of the first layer of holographic material may bephysically coupled to a first surface of a first layer of substrate anda first surface of the second layer of holographic material may bephysically coupled to a first surface of a second layer of substrate,wherein adhering the first layer of holographic material and the secondlayer of holographic material may further include: adhering a secondsurface of the first layer of holographic material to a second surfaceof the second layer of substrate, the second surface of the first layerof holographic material opposite the first surface of the first layer ofholographic material across a thickness of the first layer ofholographic material, and the second surface of the second layer ofsubstrate opposite the first surface of the second layer of substrateacross a thickness of the second layer of substrate, and wherein themethod further includes: adhering a second surface of the second layerof holographic material to a first surface of a third layer ofsubstrate, the second surface of the second layer of holographicmaterial opposite the first surface of the second layer of holographicmaterial across a thickness of the second layer of holographic material.

The method may further include physically coupling the holographicoptical element to the eyeglass lens. The manner of coupling theholographic optical element to the eyeglass lens may be selected fromthe group consisting of: adhering the holographic optical element to asurface of the eyeglass lens, embedding the holographic optical elementbetween two halves of an eyeglass lens, and forming an eyeglass lensaround the holographic optical element.

A wearable heads-up display (WHUD) may be summarized as including: asupport structure that in use is worn on a head of a user, the supportstructure having the general shape and appearance of an eyeglass frame,at least one eyeglass lens carried by the support structure, aholographic optical element physically coupled to the at least oneeyeglass lens and positioned in a field of view of the user when thesupport structure is worn on the head of the user, the holographicoptical element comprising: a first layer of holographic material thatincludes a first hologram and a second hologram; and a second layer ofholographic material that includes at least a third hologram, whereineach of the first hologram, the second hologram, and the third hologramhas a respective index modulation of at least 0.016, and wherein: thefirst hologram is responsive to light in a first waveband andunresponsive to light outside of the first waveband, the second hologramis responsive to light in a second waveband and unresponsive to lightoutside of the second waveband, the third hologram is responsive tolight in a third waveband and unresponsive to light outside of the thirdwaveband, wherein the first waveband, the second waveband, and the thirdwaveband are distinct and non-overlapping; and a laser projector carriedby the support structure, the laser projector comprising: a first laserdiode to output laser light in the first waveband, a second laser diodeto output laser light in the second waveband, a third laser diode tooutput laser light in the third waveband, a beam combiner to combine thelaser light from the laser diodes into an aggregate beam, and at leastone controllable mirror to scan the aggregate beam over the holographicoptical element. The first waveband, the second waveband, and the thirdwaveband may include: a red waveband comprising light of redwavelengths, a green waveband comprising light of green wavelengths, anda blue waveband comprising light of blue wavelengths.

The at least a third hologram may include a fourth hologram that isresponsive to light in a fourth waveband and unresponsive to lightoutside of the third waveband, wherein the fourth waveband is distinctfrom the first waveband, the second waveband, and the third waveband,with no overlap therebetween, and the laser projector further includes afourth laser diode to output laser light in a fourth waveband. The firstwaveband, the second waveband, the third waveband, and the fourthwaveband may include: a red waveband comprising light of redwavelengths, a green waveband comprising light of green wavelengths, ablue waveband comprising light of blue wavelengths, and an infraredwaveband comprising light of infrared wavelengths.

The at least one eyeglass lens and the holographic optical element maybe curved. A respective diffraction efficiency of each of the firsthologram, the second hologram, and the third hologram may be at least15%. The WHUD of claim 19 wherein a respective angular bandwidth of eachof the first hologram, the second hologram, and the third hologram maybe at least 12°. The first layer of holographic material and the secondlayer of holographic material may have a thickness not greater than 8μm. The holographic material may be a photopolymer.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, identical reference numbers identify similar elementsor acts. The sizes and relative positions of elements in the drawingsare not necessarily drawn to scale. For example, the shapes of variouselements and angles are not necessarily drawn to scale, and some ofthese elements are arbitrarily enlarged and positioned to improvedrawing legibility. Further, the particular shapes of the elements asdrawn are not necessarily intended to convey any information regardingthe actual shape of the particular elements, and have been solelyselected for ease of recognition in the drawings.

FIG. 1 is a schematic diagram of a holographic optical element inaccordance with the present systems, devices, and methods.

FIG. 2 is a schematic diagram of a holographic optical element with afirst layer of holographic material, a second layer of holographicmaterial, and a first layer of substrate, a second layer of substrate,and a third layer of substrate in accordance with the present systems,devices, and methods.

FIG. 3 is a top-view illustrative diagram of a wearable heads-up displaywith a laser projector and a curved holographic optical element inaccordance with the present systems, devices, and methods.

FIG. 4 is a flow diagram of a method of producing a holographic opticalelement wherein each hologram has an index modulation of at least 0.016in accordance with the present systems, devices, and methods.

FIG. 5 is an isometric view of a wearable heads-up display withholographic optical element and a laser projector, with a detailed viewof a portion thereto, in accordance with the present systems, devices,and methods.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various disclosedembodiments. However, one skilled in the relevant art will recognizethat embodiments may be practiced without one or more of these specificdetails, or with other methods, components, materials, etc. In otherinstances, well-known structures associated with portable electronicdevices and head-worn devices, have not been shown or described indetail to avoid unnecessarily obscuring descriptions of the embodiments.

Unless the context requires otherwise, throughout the specification andclaims which follow, the word “comprise” and variations thereof, suchas, “comprises” and “comprising” are to be construed in an open,inclusive sense, that is as “including, but not limited to.”

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structures, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

As used in this specification and the appended claims, the singularforms “a,” “an,” and “the” include plural referents unless the contentclearly dictates otherwise. It should also be noted that the term “or”is generally employed in its broadest sense, that is as meaning “and/or”unless the content clearly dictates otherwise.

The headings and Abstract of the Disclosure provided herein are forconvenience only and do not interpret the scope or meaning of theembodiments.

The various embodiments described herein provide systems, devices, andmethods for holographic optical elements and are particularlywell-suited for use in wearable heads-up displays.

FIG. 1 is a schematic diagram of a holographic optical element (HOE) 100in accordance with the present systems, devices, and methods. HOE 100includes a first layer of holographic material 111 and a second layer ofholographic material 112. HOE 100 may be curved. The holographicmaterial may be a photopolymer. First layer of holographic material 111and second layer of holographic material 112 may both be less than 8 pmthick. First layer of holographic material 111 includes a first hologramand a second hologram, and second layer of holographic material 112includes a third hologram and a fourth hologram. The first hologram isresponsive to light in a first waveband, the second hologram isresponsive to light in a second waveband, the third hologram isresponsive to light in a third waveband, and the fourth hologram isresponsive to light in a fourth waveband. The first waveband, secondwaveband, third waveband, and fourth waveband are all distinct from oneanother with no overlap between them. The first hologram, the secondhologram, the third hologram, and the fourth hologram each have arespective index modulation of at least 0.016. Therefore, the respectiveindex modulation of each of first layer of holographic material 111 andsecond layer of holographic material 112 is at least 0.032. Currentlyavailable holographic materials do not have available index modulationsmuch greater than 0.045. Therefore, if the first hologram, the secondhologram, the third hologram, and the fourth hologram were all recordedin a single layer it would be impossible to achieve respective indexmodulations greater than 0.016, as this would require a holographicmaterial capable of index modulation greater than 0.064. Distributingthe holograms across two layers of holographic material enables greaterindex modulation for each hologram. In one embodiment, the indexmodulations of the first hologram, the second hologram, the thirdhologram, and the fourth hologram may be approximately equal (+/−0.002).In another embodiment, the respective index modulation may besignificantly different for one or more of the first hologram, thesecond hologram, the third hologram, or the fourth hologram. The firsthologram, the second hologram, the third hologram, and the fourthhologram may each have a respective diffraction efficiency of at least15%, and a respective angular bandwidth of at least 12°. Bothdiffraction efficiency and angular bandwidth are affected by thethickness of the holographic material, with diffraction efficiencydecreasing as thickness decreases and angular bandwidth increasing asthickness decreases. Therefore, if the first hologram, the secondhologram, the third hologram, and the fourth hologram were all recordedin a single layer it may be impossible to achieve diffractionefficiencies for each hologram of at least 15% while simultaneouslyachieving angular bandwidths of at least 12°. Distributing the hologramsacross two layers of holographic material enables the layers ofholographic material to be thinner and results in greater diffractionefficiency and angular bandwidth for each hologram. In HOE 100 the firstwaveband comprises light of red wavelengths, the second wavebandcomprises light of green wavelengths, the third waveband comprises lightof blue wavelengths, and the fourth waveband comprises light of infraredwavelengths. A light beam 120 is incident on HOE 100. Light beam 120includes light of red wavelengths, green wavelengths, blue wavelengths,and infrared wavelengths. When light beam 120 is incident on a specificarea of HOE 100 at a specific angle it is reflected from HOE 100. Aperson of skill in the art will appreciate that the hologram could be atransmission hologram which transmits light instead of a reflectionhologram which reflects light. In FIG. 1, four individual light signalsfrom beam 120 are shown. Light signal 121 comprises light of redwavelengths and is incident on first layer of holographic material 111such that light signal 121 is reflected by the first hologram. Lightsignal 122 comprises light of green wavelengths and is incident on firstlayer of holographic material 111 such that light signal 122 isreflected by the second hologram. Light signal 123 comprises light ofblue wavelengths and is incident on second layer of holographic material112 such that light signal 123 is reflected by the third hologram. Lightsignal 124 comprises light of infrared wavelengths and is incident onsecond layer of holographic material 112 such that light signal 124 isreflected by the fourth hologram. In embodiments that do not requireresponsiveness to a fourth distinct waveband (e.g., infraredwavelengths), second layer of holographic material 112 may not include afourth hologram. In such an embodiment the third hologram would stillhave an index modulation of at least 0.016, a diffraction efficiency ofat least 15%, and an angular bandwidth of at least 12°.

FIG. 2 is a schematic diagram of a holographic optical element (HOE) 200with a first layer of holographic material 211, a second layer ofholographic material 212, and a first layer of substrate 231, a secondlayer of substrate 232, and a third layer of substrate 233 in accordancewith the present systems, devices, and methods. The first layer ofholographic material 211 and the second layer of holographic material212 are similar to first layer of holographic material 111 and secondlayer of holographic material 112 of FIG. 1, respectively. Theholographic material may be a photopolymer. First layer of holographicmaterial 211 is recorded with a first hologram and a second hologram,and second layer of holographic material 212 is recorded with a thirdhologram and a fourth hologram. The first hologram, second hologram,third hologram, and fourth hologram each have a respective indexmodulation of at least 0.016. Therefore, the respective index modulationof each of first layer of holographic material 211 and second layer ofholographic material 212 is at least 0.032. Each of the first hologram,the second hologram, the third hologram, and the fourth hologram has arespective diffraction efficiency of at least 15%, and a respectiveangular bandwidth of at least 12°. The first hologram is responsive tolight in a first waveband, the second hologram is responsive to light ina second waveband, the third hologram is responsive to light in a thirdwaveband, and the fourth hologram is responsive to light in a fourthwaveband. The first waveband, second waveband, third waveband, andfourth waveband are all distinct from one another with no overlapbetween them. Each of first layer of holographic material 211 and secondlayer of holographic material 212 has at least a first surface and asecond surface. The first surface and the second surface of each layerof holographic material are positioned opposite one another across athickness of the layer of holographic material. The three layers ofsubstrate 231, 232, and 233 may be polycarbonate, polyamide, polyimide,or triacetate. Each layer of substrate has at least a first surface anda second surface positioned opposite one another across a thickness ofthe layer of substrate. The first surface of first layer of substrate231 is physically coupled to the first surface of first layer ofholographic material 211. The first surface of second layer of substrate232 is physically coupled to the second surface of first layer ofholographic material 211. The second surface of second layer ofsubstrate 232 is physically coupled to the first surface of second layerof holographic material 212. The first surface of third layer ofsubstrate 233 is physically coupled to the second surface of secondlayer of holographic material 212. The dimensions of the layers ofholographic materials and the layers of substrate are for illustrativepurposes only and are not meant to imply that any of the dimensions ofthe layers of holographic material or the layers of substrate areidentical or similar to one another. The designation of a surface as the“first” surface or the “second” surface of either a layer of holographicmaterial or a layer of substrate is solely used for clarity indescription. HOE 200 may be a planar or curved holographic opticalelement and each layer of holographic material and layer of substratemay therefore be planar if HOE 200 is planar or curved if HOE 200 iscurved.

FIG. 3 is a top-view illustrative diagram of a wearable heads-up display(WHUD) 300 with a laser projector 350 and a curved holographic opticalelement (HOE) 310 in accordance with the present systems, devices, andmethods. Laser projector 350 includes a red laser diode 351, a greenlaser diode 352, a blue laser diode 353, an infrared laser diode 354, abeam combiner 355, and a controllable mirror 356 to scan an aggregatebeam 320. HOE 310 is physically coupled to a curved eyeglass lens 340and includes first layer of holographic material 311 and second layer ofholographic material 312. The holographic material may be aphotopolymer. First layer of holographic material 311 includes a firsthologram and a second hologram. Second layer of holographic material 312includes a third hologram and a fourth hologram. Each hologram has anindex modulation of at least 0.016, a diffraction efficiency of at least15%, and an angular bandwidth of at least 12°. The first hologram isresponsive to light in a first waveband comprising light of redwavelengths, the second hologram is responsive to light in a secondwaveband comprising light of green wavelengths, the third hologram isresponsive to light in a third waveband comprising light of bluewavelengths, and the fourth hologram is responsive to light in a fourthwaveband comprising light of infrared wavelengths. In operation, laserdiode 351 outputs red laser light in the first waveband, laser diode 352outputs green laser light in the second waveband, laser diode 353outputs blue laser light in the third waveband, and laser diode 354outputs infrared laser light in the fourth waveband. Beam combiner 355may be comprised of reflective mirrors, dichroic mirrors, and/or beamsplitters and combines the laser light output from laser diodes 351,352, 353, and 354 into aggregate beam 320. Aggregate beam 320 isdirected towards controllable mirror 356 which scans the laser lightonto HOE 310. The path of aggregate beam 320 from controllable mirror356 to HOE 310 is shown as two arrows to represent the scan range ofaggregate beam 320 on HOE 310. Red light signals 321 (dotted linearrows; only one line is numbered to reduce clutter) are reflected bythe first hologram in first layer of holographic material 311 towards aneye 370 of a user when WHUD 300 is worn on the head of the user. Greenlight signals 322 (small dashed line arrows; only one line is numberedto reduce clutter) are reflected by the second hologram in first layerof holographic material 311 towards eye 370. Blue light signals 323(large dashed line arrows; only one line is numbered to reduce clutter)are reflected by the third hologram in second layer of holographicmaterial 312 towards eye 370. Infrared light signals 324 (dashed anddotted line arrows; only one line is numbered to reduce clutter) arereflected by the fourth hologram in second layer of holographic material312 towards eye 370. Light reflected from HOE 310 which is incident atpupil 371 of eye 370 is visible to the user. Light signals 321, 322,323, and 324 are reflected by HOE 310 because they are of a specificwavelength and are incident on holographic optical element 310 at aspecific angle that the respective first hologram, second hologram,third hologram, and fourth hologram are responsive to. The user is ableto see both the light signals generated by WHUD 300 and theirenvironment as eyeglass lens 340, second layer of holographic material312, and first layer of holographic material 311 are transparent toexternal light 360. Eyeglass lens 340 and HOE 310 are shown anddescribed in FIG. 3 as curved but a person of skill in the art willappreciate that they may be flat or planar. A person of skill in the artwill also appreciate that the first waveband, second waveband, thirdwaveband, and fourth waveband may not be a red waveband, a greenwaveband, a blue waveband, and an infrared waveband, respectively, andcan be comprised of any range of wavelengths, in the visible, infrared,or UV ranges, and that although the wavebands in FIG. 3 are distinct andnon-overlapping in other embodiments the wavebands may overlap. HOE 310may include layers of substrate as described in FIG. 2.

FIG. 4 is a flow diagram of a method 400 of producing a holographicoptical element (HOE) wherein each hologram has an index modulation ofat least 0.016 in accordance with the present systems, devices, andmethods. The HOE of FIG. 4 may be substantially similar to HOE 100 ofFIG. 1, and HOE 310 of FIG. 3 and generally includes a first layer ofholographic material and a second layer of holographic material whereinthe first layer of holographic material includes a first hologramresponsive to light in a first waveband, and a second hologramresponsive to light in a second waveband, and wherein the second layerof holographic material includes a third hologram responsive to light ina third waveband, and a fourth hologram responsive to light in a fourthwaveband. The first waveband, second waveband, third waveband, andfourth waveband are all distinct and non-overlapping although a personof skill in the art will appreciate that the wavebands could overlap. Asin FIGS. 1 and 3 the first waveband may comprise light of redwavelengths, the second waveband may comprise light of blue wavelengths,the third waveband may comprise light of green wavelengths, and thefourth waveband may comprise light of infrared wavelengths. Method 400includes acts 401, 402, 403, 404, and 405, though those of skill in theart will appreciate that in alternative embodiments certain acts may beomitted and/or additional acts may be added. Those of skill in the artwill also appreciate that the illustrated order of the acts is shown forexemplary purposes only and may change in alternative embodiments.

At 401, the first layer of holographic material is mounted onto a planartransparent surface. The first layer of holographic material may have atleast a first surface and a second surface, the second surfacepositioned across a thickness of the first layer of holographic materialfrom the first surface, wherein the first surface of the first layer ofholographic material is physically coupled to a first layer ofsubstrate. The first layer of substrate may have at least a firstsurface and a second surface, the second surface positioned across athickness of the first layer of substrate from the first surface and thefirst surface of the layer of substrate may be physically coupled to thefirst surface of the first layer of holographic material.

At 402, the first hologram and the second hologram are recorded in thefirst layer of holographic material by exposing the first layer ofholographic material to light in the first waveband and light in thesecond waveband simultaneously. The specific angles of incidence of thelight on the first layer of holographic material will determine theangles of incidence of light that the first hologram and the secondhologram are responsive to. If the light in the first waveband and thelight in the second waveband were not incident on the first layer ofholographic material simultaneously the resulting first hologram andsecond hologram may not be evenly distributed throughout the first layerof holographic material. For example, if the holographic material is aphotopolymer wherein monomers react to light to create polymers, thenexposing the holographic material to light sequentially could result inmore polymers that are responsive to the first exposure waveband thanare responsive to the second exposure waveband. The light in the firstwaveband has a first power and the light in the second waveband has asecond power such that when the first layer of holographic material issimultaneously exposed to the light in the first waveband and the lightin the second waveband for a first length of time the index modulationof each of the first hologram and the second hologram is at least 0.016.The power of the light multiplied by the exposure time (in seconds)equals the total energy of light incident on the holographic material.These parameters can be used to determine a value of energy per squaredimension of holographic material that results in maximum indexmodulation. The energy of laser light may be measured in millijoules andthe dimension may be measured in centimeters resulting in an idealmJ/cm². This value may be achieved using different combinations of powerof laser light and exposure time. That is, an ideal mJ/cm² of 48 may beachieved by exposing the holographic material to 12 mW for 4 seconds, 16mW for 3 seconds, 6 mW for 8 seconds, etc. A person of skill in the artwill appreciate that the particular ideal combination of mW and secondsmay further depend on the wavelength of light, the size of the beam, thethickness of the holographic material, etc., and that not everycombination of power and time that results in the ideal mJ/cm² mayresult in maximum index modulation. The first hologram and the secondhologram may also each have diffraction efficiencies of at least 15% andangular bandwidths of at least 12°.

At 403, the second layer of holographic material is mounted onto aplanar transparent surface. The second layer of holographic material mayhave at least a first surface and a second surface, the second surfacepositioned across a thickness of the second layer of holographicmaterial from the first surface, wherein the first surface of the secondlayer of holographic material is physically coupled to a second layer ofsubstrate. The second layer of substrate may have at least a firstsurface and a second surface, the second surface positioned across athickness of the second layer of substrate from the first surface andthe first surface of the layer of substrate may be physically coupled tothe first surface of the second layer of holographic material.

At 404, the third hologram and the fourth hologram are recorded in thesecond layer of holographic material by exposing the first layer ofholographic material to light in the third waveband and light in thefourth waveband simultaneously. The specific angle of incidence of thelight on the second layer of holographic material will determine theangles of incidence of light to which the third hologram and fourthhologram are responsive. The light in the third waveband has a thirdpower and the light in the fourth waveband has a fourth power such thatwhen the second layer of holographic material is simultaneously exposedto the light in the third waveband and the light in the fourth wavebandfor a second length of time the index modulation of each of the thirdhologram and the fourth hologram is at least 0.016. The power of thelight multiplied by the exposure time (in seconds) equals the totalenergy of light incident on the holographic material. These parameterscan be used to determine a value of energy per square dimension ofholographic material that results in maximum index modulation, asdescribed above at act 402. The third hologram and the fourth hologrammay also each have diffraction efficiencies of at least 15% and angularbandwidths of at least 12°. In another implementation, the second layerof holographic material may only be recorded with a third hologram andnot a fourth hologram, wherein the third hologram still has an indexmodulation of at least 0.016, a diffraction efficiency of at least 15%,and an angular bandwidth of at least 12°.

At 405, the first layer of holographic material is adhered to the secondlayer of holographic material. Where the first layer of holographicmaterial and the second layer of holographic material are physicallycoupled to a first layer of substrate and a second layer of substraterespectively, the first layer of holographic material and the secondlayer of holographic material may be adhered by physically coupling thesecond surface of the first layer of holographic material to the secondsurface of the second layer of substrate. Alternatively, the first layerof holographic material may be adhered to the second layer ofholographic material by physically coupling the second surface of thesecond layer of holographic material to the second surface of the firstlayer of substrate. A third layer of substrate may also be added to theHOE which already includes two layers of substrate. The third layer ofsubstrate may have a first surface and a second surface positionedopposite one another across a thickness of the layer. The first surfaceof the third layer of substrate may be physically coupled to either thesecond surface of the first layer of holographic material or the secondsurface of the second layer of holographic material depending on whichlayer of holographic material has a free second surface followingadhesion of the first layer of holographic material to the second layerof holographic material.

The HOE may be physically coupled to an eyeglass lens and the method ofproducing the HOE may further include adhering the HOE to the eyeglasslens, embedding the HOE between two halves of an eyeglass lens, orforming an eyeglass lens around the HOE.

A person of skill in the art will appreciate that if the fourth wavebandcomprises light of infrared wavelengths the fourth hologram may need tobe recorded by means other than exposing the holographic material tolight of infrared wavelengths.

FIG. 5 is an isometric view of a wearable heads-up display (WHUD) 500with holographic optical element (HOE) 510 and a laser projector 550,with a detailed view of a portion thereto, in accordance with thepresent systems devices and methods. WHUD 500 includes a supportstructure 501 that is worn on the head of a user, at least one eyeglasslens 502 carried by the support structure, a HOE 510 physically coupledto eyeglass lens 502, and a laser projector 550. HOE 510 is positionedin the field of view of an eye of the user when the support structure isworn on the head of the user. HOE 510 includes a first layer ofholographic material and a second layer of holographic material. Thefirst layer of holographic material includes a first hologram responsiveto light in a first waveband and unresponsive to light outside of thefirst waveband a second hologram responsive to light in a secondwaveband and unresponsive to light outside the second waveband. Thesecond layer of holographic material includes a third hologramresponsive to light in a third waveband and unresponsive to lightoutside the third waveband and a fourth hologram responsive to light ina fourth waveband and unresponsive to light outside the fourth waveband.The first waveband, second waveband, third waveband, and fourth wavebandare all distinct and non-overlapping. The first hologram, secondhologram, third hologram, and fourth hologram each have an indexmodulation of at least 0.016. Each hologram may have a diffractionefficiency of at least 15% and an angular bandwidth of at least 12°. Thefirst waveband comprises light of red wavelengths, the second wavebandcomprises light of green wavelengths, the third waveband comprises lightof blue wavelengths, and the fourth waveband comprises light of infraredwavelengths. The laser projector (magnified in box) includes a red laserdiode 551 to generate laser light in the first waveband, a green laserdiode 552 to generate laser light in the second waveband, a blue laserdiode 553 to generate laser light in the third waveband, a fourth laserdiode 554 to generate laser light in the fourth waveband, a beamcombiner 555 to combine the laser light into an aggregate beam, and atleast one controllable mirror (not shown) to scan the aggregate beamtowards HOE 510. WHUD 500 operates as follows.

Red laser diode 551 generates red laser light, green laser diode 552generates green laser light, blue laser diode 553 generates green laserlight, and infrared laser diode 554 generates infrared laser light.Laser projector 510 may include a processor and a non-transitoryprocessor-readable storage medium to control the generation of light bylaser diodes 551, 552, 553, and 554. The red, green, blue, and infraredlaser light in combined into an aggregate beam by beam combiner 555.Beam combiner may be comprised of any number of beam splitters, dichroicmirrors, and reflective mirrors. The aggregate beam is directed by thelast element of beam combiner 555 towards a controllable mirror whichscans the aggregate beam onto HOE 510. Laser projector 550 may includeone or more controllable mirrors that may be MEMs mirrors. As theaggregate beam is scanned onto HOE 510, light that is incident on theHOE at the correct angle and the correct wavelength is reflected towardsthe eye of the user. That is light of a red wavelength that is incidenton the first hologram at an angle the first hologram is responsive towill reflect towards the eye of the user to create at least part of animage at the eye of the user. Light of a green wavelength that isincident on the second hologram at an angle that the second hologram isresponsive to and light of a blue wavelength that is incident on thethird hologram at an angle that the third hologram is responsive to willalso be reflected towards the eye of the user to create at least a partof the same image, if the light is incident at the eye of the usersimultaneously. In this way, a full color image can be created at theeye of the user. Light of an infrared wavelength that is incident on thefourth hologram at an angle that the fourth hologram is responsive towill be reflected towards the eye of the user but is not visible to theuser and therefore does not contribute to the image. The infrared lightmay be used for other purposes such as tracking the movement of the eyeof the user.

A person of skill in the art will appreciate that the variousembodiments for holographic optical elements described herein may beapplied in non-WHUD applications. For example, the present systems,devices, and methods may be applied in non-wearable heads-up displaysand/or in other applications that may or may not include a visibledisplay.

A person of skill in the art will appreciate that the variousembodiments for holographic optical elements described herein may beapplied in different ways in WHUD applications. That is, a HOE asdescribed herein, may be used to guide light along an optical pathwaywithin a WHUD wherein the light is directed by the HOE to anotheroptical element of the WHUD and not directly to an eye of a user.Therefore, a HOE, as described herein, may not be physically coupled toa lens of a WHUD but may be present elsewhere within or on the WHUD.

A person of skill in the art will appreciate that light sources otherthan laser diodes may be used in a WHUD, including but not limited to:light-emitting diodes (LED), organic light-emitting diodes (OLED),microLEDs, and/or microdisplays.

In some implementations, one or more optical fiber(s), waveguides, orlightguides may be used to guide light signals along some of the pathsillustrated herein.

The WHUDs described herein may include one or more sensor(s) (e.g.,microphone, camera, thermometer, compass, altimeter, and/or others) forcollecting data from the user's environment. For example, one or morecamera(s) may be used to provide feedback to the processor of the WHUDand influence where on the display(s) any given image should bedisplayed.

The WHUDs described herein may include one or more on-board powersources (e.g., one or more battery(ies)), a wireless transceiver forsending/receiving wireless communications, and/or a tethered connectorport for coupling to a computer and/or charging the one or more on-boardpower source(s). The WHUDs described herein may receive and respond tocommands from the user in one or more of a variety of ways, includingwithout limitation: voice commands through a microphone; touch commandsthrough buttons, switches, or a touch sensitive surface; and/orgesture-based commands through gesture detection systems as describedin, for example, U.S. Non-Provisional patent application Ser. No.14/155,087, U.S. Non-Provisional patent application Ser. No. 14/155,107,PCT Patent Application PCT/US2014/057029, U.S. Provisional PatentApplication Ser. No. 62/236,060, and/or U.S. Provisional PatentApplication Ser. No. 62/487,303, all of which are incorporated byreference herein in their entirety.

Throughout this specification and the appended claims, the term“carries” and variants such as “carried by” or “carrying” are generallyused to refer to a physical coupling between two objects. The physicalcoupling may be direct physical coupling (i.e., with direct physicalcontact between the two objects) or indirect physical coupling mediatedby one or more additional objects. Thus the term carries and variantssuch as “carried by” are meant to generally encompass all manner ofdirect and indirect physical coupling.

Throughout this specification and the appended claims the term“communicative” as in “communicative pathway,” “communicative coupling,”and in variants such as “communicatively coupled,” is generally used torefer to any engineered arrangement for transferring and/or exchanginginformation. Exemplary communicative pathways include, but are notlimited to, electrically conductive pathways (e.g., electricallyconductive wires, electrically conductive traces), magnetic pathways(e.g., magnetic media), and/or optical pathways (e.g., optical fiber),and exemplary communicative couplings include, but are not limited to,electrical couplings, magnetic couplings, and/or optical couplings.

Throughout this specification and the appended claims, infinitive verbforms are often used. Examples include, without limitation: “to detect,”“to provide,” “to transmit,” “to communicate,” “to process,” “to route,”and the like. Unless the specific context requires otherwise, suchinfinitive verb forms are used in an open, inclusive sense, that is as“to, at least, detect,” to, at least, provide,” “to, at least,transmit,” and so on.

The above description of illustrated embodiments, including what isdescribed in the Abstract, is not intended to be exhaustive or to limitthe embodiments to the precise forms disclosed. Although specificembodiments of and examples are described herein for illustrativepurposes, various equivalent modifications can be made without departingfrom the spirit and scope of the disclosure, as will be recognized bythose skilled in the relevant art. The teachings provided herein of thevarious embodiments can be applied to other portable and/or wearableelectronic devices, not necessarily the exemplary wearable electronicdevices generally described above.

For instance, the foregoing detailed description has set forth variousembodiments of the devices and/or processes via the use of blockdiagrams, schematics, and examples. Insofar as such block diagrams,schematics, and examples contain one or more functions and/oroperations, it will be understood by those skilled in the art that eachfunction and/or operation within such block diagrams, flowcharts, orexamples can be implemented, individually and/or collectively, by a widerange of hardware, software, firmware, or virtually any combinationthereof. In one embodiment, the present subject matter may beimplemented via Application Specific Integrated Circuits (ASICs).However, those skilled in the art will recognize that the embodimentsdisclosed herein, in whole or in part, can be equivalently implementedin standard integrated circuits, as one or more computer programsexecuted by one or more computers (e.g., as one or more programs runningon one or more computer systems), as one or more programs executed by onone or more controllers (e.g., microcontrollers) as one or more programsexecuted by one or more processors (e.g., microprocessors, centralprocessing units, graphical processing units, field programmable gatearray, application specific integrated circuit, programmable logiccontroller), as firmware, or as virtually any combination thereof, andthat designing the circuitry and/or writing the code for the softwareand or firmware would be well within the skill of one of ordinary skillin the art in light of the teachings of this disclosure.

When logic is implemented as software and stored in memory, logic orinformation can be stored on any processor-readable medium for use by orin connection with any processor-related system or method. In thecontext of this disclosure, a memory is a processor-readable medium thatis an electronic, magnetic, optical, or other physical device or meansthat contains or stores a computer and/or processor program. Logicand/or the information can be embodied in any processor-readable mediumfor use by or in connection with an instruction execution system,apparatus, or device, such as a computer-based system,processor-containing system, or other system that can fetch theinstructions from the instruction execution system, apparatus, or deviceand execute the instructions associated with logic and/or information.

In the context of this specification, a “non-transitoryprocessor-readable medium” can be any element that can store the programassociated with logic and/or information for use by or in connectionwith the instruction execution system, apparatus, and/or device. Theprocessor-readable medium can be, for example, but is not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus or device. More specific examples (anon-exhaustive list) of the computer readable medium would include thefollowing: a portable computer diskette (magnetic, compact flash card,secure digital, or the like), volatile memory such as Random AccessMemory (RAM), memory caches, processor registers; nonvolatile memorysuch as Read Only Memory, EEPROM, Flash memory, magnetic disks, opticaldisks; a portable compact disc read-only memory (CDROM), digital tape,and other non-transitory media.

The various embodiments described above can be combined to providefurther embodiments. To the extent that they are not inconsistent withthe specific teachings and definitions herein, all of the U.S. patents,U.S. patent application publications, U.S. patent applications, foreignpatents, foreign patent applications and non-patent publicationsreferred to in this specification and/or listed in the Application DataSheet which are owned by Thalmic Labs Inc., including but not limitedto: US Patent Application Publication No. 2016-0377866 A1 US, US PatentApplication Publication No. 2016-0377865, US Patent ApplicationPublication No. US 2014-0198034 A1, US Patent Application PublicationNo. US 2016-0238845 A1, US Patent Application Publication No. US2014-0198035 A1, Non-Provisional patent application Ser. No. 15/046,234,U.S. Non-Provisional patent application Ser. No. 15/046,254, U.S.Non-Provisional patent application Ser. No. 15/145,576, U.S.Non-Provisional patent application Ser. No. 15/145,609, U.S.Non-Provisional patent application Ser. No. 15/147,638, U.S.Non-Provisional patent application Ser. No. 15/145,583, U.S.Non-Provisional patent application Ser. No. 15/256,148, U.S.Non-Provisional patent application Ser. No. 15/167,458, U.S.Non-Provisional patent application Ser. No. 15/167,472, U.S.Non-Provisional patent application Ser. No. 15/167,484, U.S.Non-Provisional patent application Ser. No. 15/381,883, U.S.Non-Provisional patent application Ser. No. 15/331,204, U.S.Non-Provisional patent application Ser. No. 15/282,535, U.S. ProvisionalPatent Application Ser. No. 62/271,135 U.S. Provisional PatentApplication Ser. No. 62/268,892, U.S. Provisional Patent ApplicationSer. No. 62/322,128, U.S. Provisional Patent Application Ser. No.62/420,368, U.S. Provisional Patent Application Ser. No. 62/420,371,U.S. Provisional Patent Application Ser. No. 62/420,380, U.S.Provisional Patent Application Ser. No. 62/438,725, U.S. ProvisionalPatent Application Ser. No. 62/374,181, U.S. Provisional PatentApplication Ser. No. 62/482,062, U.S. Provisional Patent ApplicationSer. No. 62/557,551, U.S. Provisional Patent Application Ser. No.62/557,554, U.S. Provisional Patent Application Ser. No. 62/565,677,U.S. Provisional Patent Application Ser. No. 62/573,978, and U.S.Provisional Patent Application Ser. No. 62/487,303, are incorporatedherein by reference, in their entirety. Aspects of the embodiments canbe modified, if necessary, to employ systems, circuits and concepts ofthe various patents, applications and publications to provide yetfurther embodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

1. A method of producing a holographic optical element that comprises afirst layer of holographic material and a second layer of holographicmaterial wherein the first layer includes a first hologram responsive toa first waveband of light and a second hologram responsive to a secondwaveband of light, and the second layer includes a third hologramresponsive to a third waveband of light, wherein each of the firstwaveband, the second waveband, and the third waveband is distinct andnon-overlapping, the method comprising: mounting the first layer ofholographic material on a planar transparent surface; recording thefirst hologram and the second hologram in the first layer of holographicmaterial, wherein recording includes exposing the first layer ofholographic material to light in the first waveband and light in thesecond waveband simultaneously to provide respective index modulationsof at least 0.016 to the first hologram and the second hologram;mounting the second layer of holographic material on a planartransparent surface; recording the third hologram in the holographicmaterial wherein recording includes exposing the second layer ofholographic material to light in the third waveband to provide an indexmodulation of at least 0.016 to the third hologram; and adhering thefirst layer of holographic film and the second layer of holographicfilm.
 2. The method of claim 1 wherein: recording the first hologram andthe second hologram in the first layer of holographic material furtherincludes: simultaneously exposing the first layer of holographicmaterial to light in the first waveband having a first power and lightin the second waveband having a second power for a first length of timeto provide an index modulation of 0.016 to both the first hologram andthe second hologram; and recording the third hologram in the secondlayer of holographic material further includes: exposing the secondlayer of holographic material to light in the third waveband having athird power for a second length of time to provide an index modulationof 0.016 to the third hologram.
 3. The method of claim 1 wherein thesecond layer of holographic film further includes a fourth hologramresponsive to a fourth waveband of light, wherein the fourth waveband oflight is distinct from the first waveband, the second waveband, and thethird waveband with no overlap therebetween, the method furtherincluding: recording the fourth hologram in the second layer ofholographic material by exposing the second layer of material to lightin the fourth waveband concurrently with the recording of the thirdhologram to provide an index modulation of at least 0.016 to the fourthhologram.
 4. The method of claim 1 wherein a first surface of the firstlayer of holographic material is physically coupled to a first surfaceof a first layer of substrate and a first surface of the second layer ofholographic material is physically coupled to a first surface of asecond layer of substrate, and wherein adhering the first layer ofholographic material and the second layer of holographic materialfurther includes: adhering a second surface of the first layer ofholographic material to a second surface of the second layer ofsubstrate, the second surface of the first layer of holographic materialopposite the first surface of the first layer of holographic materialacross a thickness of the first layer of holographic material, and thesecond surface of the second layer of substrate opposite the firstsurface of the second layer of substrate across a thickness of thesecond layer of substrate; and wherein the method further includes:adhering a second surface of the second layer of holographic material toa first surface of a third layer of substrate, the second surface of thesecond layer of holographic material opposite the first surface of thesecond layer of holographic material across a thickness of the secondlayer of holographic material.
 5. The method of claim 1 wherein themethod further comprises: physically coupling the holographic opticalelement to the eyeglass lens.
 6. The method of claim 5 wherein themanner of coupling the holographic optical element to the eyeglass lensis selected from the group consisting of: adhering the holographicoptical element to a surface of the eyeglass lens, embedding theholographic optical element between two halves of an eyeglass lens, andforming an eyeglass lens around the holographic optical element.